Make sure that you have read/write permission when adding Bootcamp partition

Hi,

I'm using Macbook Air and installed Windows 7 using bootcamp. But when trying to add the boot camp partition in parallels I get the error:

"A disk configuration error has occurred. Make sure that you have read/write permissions for the disk."

It worked a few weeks ago but after re-installing parallels it stopped working, giving me this error message.